High hydrophobic silanized paper: Material characterization and its biodegradation through brown rot fungus.

Modifying natural polymers with silicones gives new possibilities for packaging products and waste management. In this study, the innovative papers produced were altered following the reaction of polysaccharides and organosilicon compounds. The susceptibility of the studied material to biodegradation caused by a brown-rot fungus was assessed. Strength properties by tensile strength and dynamic mechanical analysis and hydrophobic properties by water uptake test and water contact angle analysis were evaluated. Moreover, elemental analysis by ICP method was controlled. The durability against fungi and the hydrophobic properties were increased by the modification. The fungal decay resistance of the silanized paper was reduced by water storage, which allows for managing paper waste. Cellulose-based paper treated with starch-modified methyltrimethoxysilane showed potential as a packaging material due to its reduced water uptake. Possible application areas could be corrugated boxes, cellulose thermoformed products for electronics, and food packaging. However, the water-repellent effect is limited to short-term exposure in humid conditions.

The Strength and Fire Properties of Paper Sheets Made of Phosphorylated Cellulose Fibers.

Phosphorylated cellulose can be an intrinsic flame retardant and a promising alternative for halogenated fire inhibitors. In this study, the mixture of di-ammonium hydrogen phosphate (DAP) and urea (U), containing phosphate and nitrogen groups, was applied to attain fire inhibitor properties. Functional groups of cellulose were grafted with phosphorous by keeping the constant molar ratio of 1/1.2/4.9 between anhydroglucose units of cellulose/DAP/U in different concentrations of bleached kraft pulp. Phosphorus concentrations were determined using the ICP hrOES method, and paper sheets were made using the Rapid Köthen apparatus. The tensile strength of phosphorylated cellulose increased twice compared with unmodified cellulose when the phosphorous concentration increased to 10,000 g/kg. An increase in the tensile index comes from the higher freeness of pulp and cross-linking of the phosphorous group between cellulose fibers. Remarkable fire retardancy effects were achieved in cellulose concentrations above 5 wt%. The raised phosphorous concentration above 10,000 g/kg due to the phosphorylation process caused the formation of a char layer on a cellulose surface and the nonflammable gas emission. That effect was indirectly confirmed by reducing the combustion temperature and HRR by 50 and 45%, respectively. Due to increasing phosphorus concentration in cellulose sheets, cellulose's fire and strength properties increased significantly.

Influence of Nanocellulose Structure on Paper Reinforcement.

This article describes how crystalline or fibrous nanocellulose influences the mechanical properties of paper substrate. In this context, we used commercially available cellulose nanocrystals, mechanically prepared cellulose nanofibers dispersed in water or ethanol, and carboxy cellulose nanofibers. Selective reinforcement of the paper treated with the nanocellulose samples mentioned above was observed. The change in the fibre structure was assessed using scanning electron microscopy, roentgenography, and spectroscopy techniques. In addition, the effect of nanocellulose coating on physical properties was evaluated, specifically tensile index, elongation coefficient, Elmendorf tear resistance, Bendtsen surface roughness, Bendtsen air permeability, and bending strength. It can be concluded that the observed decrease in the strength properties of the paper after applying some NC compositions is due to the loss of potential disturbances in hydrogen bonds between the nanocellulose dispersed in ethanol and the paper substrate. On the other hand, significantly increased strength was observed in the case of paper reinforced with nanocellulose functionalized with carboxyl groups.

Starch-Silane Structure and Its Influence on the Hydrophobic Properties of Paper.

Starch is an inexpensive, easily accessible, and widespread natural polymer. Due to its properties and availability, this polysaccharide is an attractive precursor for sustainable products. Considering its exploitation in adhesives and coatings, the major drawback of starch is its high affinity towards water. This study aims to explain the influence of the silane-starch coating on the hydrophobic properties of paper. The analysis of the organosilicon modified starch properties showed an enhanced hydrophobic behavior, suggesting higher durability for the coatings. Molecules of silanes with short aliphatic carbon chains were easily embedded in the starch structure. Longer side chains of silanes were primarily localized on the surface of the starch structure. The best hydrophobic properties were obtained for the paper coated with the composition based on starch and methyltrimethoxysilane. This coating also improved the bursting resistance and compressive strength of the tested paper. A static contact angle higher than 115° was achieved. PDA analysis confirmed the examined material exhibited high barrier properties towards water. The results extend the knowledge of the interaction of silane compositions in the presence of starch.

Influence of Reaction Parameters on the Gelation of Silanised Linseed Oil.

The subject of this work was to characterize the catalytic course of the linseed oil silylation reaction with vinyltrimethoxysilane (VTMOS), carried out under elevated pressure and temperature conditions, and an explanation of the reasons for rapid gelation of the reaction product. To explain and describe the process, analytical methods were used, i.e., 1H and 13C NMR (nuclear magnetic resonance), GC-FID (gas chromatography coupled with flame ionisation detection), and GPC (gel permeation chromatography). Reaction products were monitored after 3, 6 and 12 h. The molar mass of the VTMOS-modified oil in only 3 h was comparable with the molar mass of the product obtained by conventional polymerisation. An increase in the reaction time resulted in further transformations resulting from the hydrolysis and condensation reactions taking place. In contrast to reactivity of soybean oil, the silanisation of linseed oil occurred much faster and without the need for cross-linking catalysts. The reason for the high reactivity of linseed oil to VTMOS and rapid gelation of the resulting product was primarily the amount of double bonds present in linseed oil and their high availability, in particular the double bond in the acid linolenic acid located at the C16 carbon.

Influence of Chemical Pre-Treatments and Ultrasonication on the Dimensions and Appearance of Cellulose Fibers.

Due to the wider use of nanocellulose in various areas of economic life, better and more optimal methods of obtaining nanocellulose are constantly being sought. Therefore, an attempt was made to evaluate the hybrid cellulose treatment, based on the use of a chemical method combined with an ultrasound of medium frequency. The study employs two different starting materials (Södra Black R cellulose or microcrystalline cellulose), two types of chemical pre-treatments (acid hydrolysis or oxidation), and two sonication durations. It was found that the reduction fiber cross-sectional dimensions was the result of prolonged exposure of cellulose to the ultrasound. From Södra Black R and the microcrystalline cellulose nanometer scale, structures were obtained in the form of isolated fibers. The TEMPO reagent accelerated the degradation process of two cellulose varieties due to its oxidizing character. The resulting products had nanofibrous structures. Cellulose degradation as a result of the combined action of sonication and TEMPO activity progressed gradually. Places of fiber degradation were characterized by their longitudinal breakage and initiated the next stages of the defibering process.

Catalyzed Reaction of Cellulose and Lignin with Methyltrimethoxysilane-FT-IR, 13C NMR and 29Si NMR Studies.

It can be found that reaction mechanisms and interactions between wood and organosilicone compounds have not been sufficiently explored. The aim of the study was to determine bonds formed between either cellulose or lignin and methyltrimethoxysilane (MTMOS) during a catalytic silanization reaction. Silanization was performed in the presence of two catalysts of a diverse mechanism of functionalization: aluminum acetylacetonate (Al(acac)3) and acetic acid (AcOH). For this purpose, FT-IR, 13C and 29Si NMR techniques were used. Cellulose silanization efficiency without a catalyst was unlikely. Lignin undergoes a silanization reaction with alkoxysilanes much easier than cellulose. The results showed new bonds between biopolymers and the silanising agent. The new bonds were confirmed by signals at the FT-IR spectra, e.g., 770 cm-1 and 1270 cm-1 (Si-CH3), and at the NMR signal coming from the T1, T2 and T3 structures. Efficiency of reaction was confirmed by atomic absorption spectroscopy (AAS) analysis.